High energy photon production in bent crystals:

the latest measurements.

1 Università degli Studi dell'Insubria, Via Valleggio 11, 22100 Como, Italy and INFN Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy.2 INFN Sezione di Ferrara and Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44100 Ferrara, Italy3 Dipartimento di Ingegneria dei Materiali e Tecnologie Industriali, Università di Trento, Via Mesiano 77, 38050 Trento, Italy4 Dipartimento di Fisica Università di Padova, Via 8 Febbraio 1848 2, 35121 Padova, Italy.5 INFN Laboratori Nazionali di Legnaro, Viale Università 2, 35020 Legnaro (PD), Italy6 INFN Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy7 Institute of High Energy Physics, Moscow Region, RU-142284 Protvino. Russia

1 Università degli Studi dell'Insubria, Via Valleggio 11, 22100 Como, Italy and INFN Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy.2 INFN Sezione di Ferrara and Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44100 Ferrara, Italy3 Dipartimento di Ingegneria dei Materiali e Tecnologie Industriali, Università di Trento, Via Mesiano 77, 38050 Trento, Italy4 Dipartimento di Fisica Università di Padova, Via 8 Febbraio 1848 2, 35121 Padova, Italy5 INFN Laboratori Nazionali di Legnaro, Viale Università 2, 35020 Legnaro (PD), Italy6 INFN Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy7 Institute of High Energy Physics, Moscow Region, RU-142284 Protvino. Russia

S. HasanS. Hasan1 1 on behalf of the INSURAD Collaboration:on behalf of the INSURAD Collaboration: A.G. AfoninA.G. Afonin77, E. Bagli, E. Bagli22, , S. BaricordiS. Baricordi22, A. Berra, A. Berra11, , D. BologniniD. Bolognini11, Yu. A. Chesnokov, Yu. A. Chesnokov77, ,

P. N. ChirkovP. N. Chirkov77, P. Dalpiaz, P. Dalpiaz22, G. Della Mea, G. Della Mea3,43,4, D. De Salvador, D. De Salvador4,54,5,, V. Guidi V. Guidi22, V. A. , V. A. MaisheevMaisheev77, A. Mazzolari, A. Mazzolari22, M. Prest, M. Prest11, E. Vallazza, E. Vallazza66, D. Vincenzi, D. Vincenzi22, I. A. Yazynin, I. A. Yazynin77

High energy photon production in bent crystals:

the latest measurements.

OutlineOutline

Measure radiation from bent crystals?WhyWhy

2009 beam test to measure the radiation emission (positrons of 120GeV)2009 beam test to measure the radiation emission (positrons of 120GeV)

How we measure deflection and radiation

Results: Channeling and Volume Reflection Comparison with theory

Going beyondGoing beyond

Multi crystals and axial effects → to increase the intensity

RadiationRadiation

Why measure radiation from bent crystals?Why measure radiation from bent crystals?

Bent crystals are devices that can be used for many applications; the most important are: beam collimation, beam extraction, beam splitting

At the moment they are addressed to hadron machines (e.g. LHC collimation)

A future application to electron-positron machines should take into account the radiation issue

The high amount of energy loss inside a bent crystal can be used to perform collimation in an electron-positron machine

The electromagnetic cascade inside a bent crystal can be exploited to design a high intensity electron-positron source

Bent crystals can be used as a high intensity photon source dedicated to nuclear physics studies or detector tests such as calibration

IntroductionIntroduction

How we measure the deflection properties:How we measure the deflection properties:

Double sided silicon microstrip detectorPhysical strip pitch: 25umResolution: 6um

High resolution goniometer (res: ~1urad)2 rotational and 2 linear movements

Tracking system

Deflection measurementsDeflection measurements

Misaligned crystal→Misaligned crystal→Amorphous behaviourAmorphous behaviour

2mm silicon strip crystal aligned along the (110) plane

Deflection measurementsDeflection measurements

Perfect alignment →Perfect alignment →channelingchanneling

Deflection measurementsDeflection measurements

Perfect alignment →Perfect alignment →dechannelingdechanneling

Deflection measurementsDeflection measurements

Tangency inside crystal Tangency inside crystal → Volume Reflection→ Volume Reflection

Deflection measurementsDeflection measurements

Tangency inside crystal Tangency inside crystal → Volume Capture→ Volume Capture

RadiationRadiation

High High energyenergy photons from bent crystals photons from bent crystals

ChannelingChanneling

VolumeVolume reflectionreflection

particles confined in the interplanar potential that perform quasi harmonic oscillations emitting radiation

particles slightly over barrier cross the crystalline plane with an angle which varies along the trajectory

RadiationRadiation

Let's measure it!Let's measure it!

September 2009, H4 beam line (CERN, SPS), 120 GeV positrons

RadiationRadiation

Let's measure itLet's measure it

positrons

muons

Identification of the primary particle

RadiationRadiation

Let's measure itLet's measure it

positrons

pθ=0.3BL

Spectrometer angular distribution Spectral distribution

Comparison calorimeter-spectrometer

RadiationRadiation

Let's measure itLet's measure it

RadiationRadiation

Let's measure itLet's measure it

It is possible to “select” an effect and measure its “radiation” properties:It is possible to “select” an effect and measure its “radiation” properties:

Multiplyingfor E

Energy loss distribution Spectral distribution

dN/dE(E) dN/dE(E) x E

Amorphous condition → bremsstrahlung

Radiation ResultsRadiation Results

ChannelingChanneling

ChannelingAmorphousBackground

Strip crystal:2mm of silicon along the beam~5m bending radius

Selected region:Channeled particle

-9 < α < 9 urad

Radiation ResultsRadiation Results

ChannelingChanneling

Enhancement with respect to amorphous

Enhancement:~15 times at ~20 GeV

ChannelingAmorphousBackground

Radiation ResultsRadiation Results

ChannelingChanneling

Average energy loss: ~11.7GeV

Average photons multiplicity: ~4

Photon multiplicity distributionfrom simulation

ChannelingAmorphousBackgroundSimulation

Radiation ResultsRadiation Results

ChannelingChanneling

Selected region:Channeled particle

-9 < α < 9 urad

The effect of bending is negligible:The effect of bending is negligible:

The same crystal with smaller bending

Strip crystal:2mm of silicon along the beam~11m bending radius

ChannelingAmorphousBackgroundSimulation same as before

Radiation ResultsRadiation Results

Volume Reflection Volume Reflection (present only in bent crystal)(present only in bent crystal)

Strip crystal:2mm of silicon along the beam~11m bending radius

Average energy loss: 11.2GeV

Average photons multiplicity: ~1.5The photons spectrum is much harder with respect to the channeling one

Enhancement:~12 times @ ~30GeV

V. ReflectionAmorphousBackgroundCalculation

Radiation ResultsRadiation Results

Volume ReflectionVolume Reflection

The effect of bending is not negligible:The effect of bending is not negligible:Strip crystal:2mm of silicon along the beam~5m bending radius

Bending radius 11m

Bending radius 5m

Average energy loss: 7.3GeV

V. ReflectionAmorphousBackgroundCalculation

Increasing the emitted energyIncreasing the emitted energy

Volume Reflection → larger angular acceptanceVolume Reflection → larger angular acceptance

Using a series of crystals to increase deflection and radiation is possible!

Different channeling peaks

MultiVR

End of measured sensitive region

The radiation energy loss shows an amplification but it is not possible either to view all the spectrum or to normalize it as the spectrometer is sensitive until ~60GeV

1st: planar alignment

2nd: axial alignment1st: planar alignment

2nd: axial alignment

VRVR

A crystal axis is the intersection of several planesIf a particle beam impinges onto the crystal at an appropiate angle, it is subject to volume reflections from subsequent planes

MVROCMVROC

Increasing emitted energyIncreasing emitted energy

Axial Axial alignmentalignment → → Multivolume reflection in one crystalMultivolume reflection in one crystal

Deflection angle ~90urad

Increasing emitted energyIncreasing emitted energy

Axial Axial alignmentalignment → → Multivolume reflection in one crystalMultivolume reflection in one crystal

1st: planar alignment

2nd: axial alignment1st: planar alignment

2nd: axial alignment

VRVR

As well as for the “crystal series” the measurement is limited by the spectrometer acceptance thus it provides only a qualitative result

MVROCMVROC

Conclusions Conclusions andand outlooks outlooks

Bent crystals → for particle deflection → radiation emission

channelingchannelingVolume ReflectionVolume Reflection

Characterized from the experimental point of view In agreement with simulation and theory

Different strategies to increase the emitted radiation are possible

Series of crystals, axial orientation Series of crystals, axial orientation (MVROC and other effects)(MVROC and other effects)

Need to measure all the spectrum till 120GeVNeed to measure all the spectrum till 120GeV

June 2010: new test beam dedicated to the axial effectsand to the electrons

Thanks to the new “photon” calorimeter the whole spectrum has beenThanks to the new “photon” calorimeter the whole spectrum has beenmeasuredmeasured, data analysis is ongoing, data analysis is ongoing

Shashlik calorimeter readout by SiPMs

Thank you for the attentionThank you for the attention

High energy photon production in bent crystals:

the latest measurements.

High energy photon production in bent crystals:

the latest measurements.

Beam

halo

Crystal in VR

Dipole

Absorber

Courtesy of A. Seryi

Particles which cross the crystal in VR lose their momentum in radiation and are deflected more by a following dipole

Backup 1Backup 1

Channeling Multi VR

Backup 2Backup 2 About normalization

Backup 3Backup 3

Confronto coherent bremstrhalung

Volume reflection

Amorphous

Background

Cut = +/- 50urad (gaussian)

Incoming angle (urad)

En

erg

y (

Ge

V)

En

erg

y (

Ge

V)

De

fle

cti

on

an

gle

(u

rad

)

st1_2.dat

Enhancement of angular acceptance